1. Field of the Invention
The present invention relates to a method for measuring a propeller surface and, more particularly, for measuring a vane surface contour of a propeller or the like. The present invention also relates to a device for measuring the vane surface contour of the propeller or the like.
2. Description of Related Art
FIG. 1 shows a conventional surface contour measuring device including a measuring module 1 and a seat 2. A propeller 3 is rotatably mounted to the seat 2 by a shaft and located below the measuring module 1. The propeller 3 includes a hub 31 and a plurality of vanes 32 formed on the hub 31. The measuring module 1 includes a measuring unit 11 and a measuring rod 41 movable in a vertical direction and having a measuring end 121.
The measuring end 121 of the measuring rod 41 is moved downward until it rests on a top surface of one of the vanes 32 due to gravitational force. The measuring end 121 moves on the top surface of the vane 32 when the propeller 3 is rotated and, thus, moved relative to the measuring end 121. Specifically, the measuring end 121 moves upward or downward in response to the contour of the top surface of the vane 32 whereas the measuring unit 11 moves vertically. Next, the measuring rod 41 is moved in the radial direction relative to the hub 31 to another position, and the propeller 3 is rotated again. Movement of the measuring rod 41 in the radial direction to a different position and rotation of the propeller 3 are repeated to obtain data corresponding to various points of the top surface contour of the vane 32. Thus, the measuring module 1 can obtain the data corresponding to the top surface contour of the vane 32 and simulate the top surface contour of the vane 32. However, the measuring module 1 can not be utilized to measure the vane surface contour of a propeller 3 whose vanes 32 are overlapped in an axial direction. Specifically, for a propeller 3 (see FIGS. 2 and 3) including an overlapped section 33 at two adjacent vanes 32, the measuring rod 41 will be impeded by the edge of an upper one of the two adjacent vanes 32. As a result, the contour of the overlapped section 33 of the lower one of the two adjacent vanes 32 can not be reached and measured.
To solve this problem, the measuring rod 41 is modified to include a bend (see FIG. 3) so that the measuring end 121 can enter the overlapped section 33 of the lower vane 32 without being impeded by the edge of the upper vane 32. However, such a measuring rod 41 with a bend can not measure a propeller 3 (see FIG. 4) having more vanes 32 and/or having a large curvature or a larger overlapped section 33. The measuring rod 41 must be changed in response to the larger curvature or larger spacing between the vanes 32, leading to inconvenient measurement.